The present invention relates generally to the design and construction of an apparatus for the introduction of a blasting media into a high velocity, high pressure fluid stream. More particularly, the present invention has one embodiment wherein a dual chambered pressure vessel has a pair of auxiliary actuated pop-up valves that are cycled at a relatively high rate to provide delivery of the blasting media to the high velocity high pressure fluid stream.
It is well known that the application of a pressurized blasting media transported by a high pressure, high velocity fluid has been utilized for well over a century for things such as the removal of paint and other coatings, removal of rust, cutting of substrates, and other surface conditioning. Many of the projects in need of surface conditioning are physically large, such as petroleum storage tanks, bridges, and buildings. Many of these projects may take a few days, weeks, or longer to complete. Further, the very nature of many of these projects is such that the structure is practically immovable and the blasting media apparatus must be brought to the job site.
Many prior conventional blasting media apparatuses have a pneumatically operated system that utilizes refillable blasting media reservoirs to furnish the blasting media. The refilling of the blasting media reservoirs in the prior designs generally require extra manpower, equipment, and lost work time while the reservoirs are being refilled. More specifically, conventional blasting pot apparatuses include a pressure vessel that is partially filled with an abrasive blasting media, and coupled to the top of the pressure vessel is a valve openable for allowing the vessel to be refilled with blasting media. After a sufficient quantity of blasting media has been accumulated within the pressure vessel, pressurized air is introduced into the vessel thereby closing the valve and forcing the blasting media into the high pressure high velocity air stream for delivery to a blasting nozzle.
A common limitation associated with conventional blast pot apparatuses is that they are batch type devices, thereby necessitating stopping the blasting operation while the pressure vessel is filled with blasting media. In an effort to increase the uninterrupted blasting time available to the machine operator many prior designers of conventional blast pot apparatuses have increased the volume and physical size of the pressure vessel in order to hold more blasting media. Thus there are numerous machines available with blasting media storage capacities of as much as twenty (20) plus tons of blasting media. However, increasing the pressure vessel size often results in a cumbersome machine that is difficult to transport to a job site and does not eliminate the inherent limitation of a batch type device that requires stopping the blasting operation in order to refill the pressure vessel with blasting media.
A blasting machine utilizing a dual chambered pressure vessel with an upper and lower reservoir has been utilized in an attempt to minimize the limitations associated with a batch type blasting machine. While some of the prior dual chambered blasting systems strive to function as continuous blasting apparatuses they have associated therewith numerous problems which has limited their acceptance in the marketplace. One limitation is associated with the pressure vessel requiring a significant amount of pressurized fluid flow in order to close the pop-up valve between the upper and lower reservoirs. During the period of closing the pop-up valve a substantial pressure drop often occurs in the pressure vessel, thereby disrupting the delivery of blasting media into the high pressure high velocity air stream. The disruption of the blasting media flow causes changes in the air flow and blasting patterns that greatly disrupt the blasting machine operators ability to maintain an efficient work rhythm.
Many dual chamber blasting media systems, in an apparent effort to minimize the above pop-up valve closing problem, have increased the volume of the pressure vessel. By continuing to increase the pressure vessels size many systems have become physically cumbersome, and the increased pressure vessel volume generally requires an increase in the fluid flow required to close the pop-up valve thereby further aggravating the pressure drop phenomenon. Further, many prior blasting media machines couple multiple working station outlets to one centralized pressure vessel, which means that if one outlet requires maintenance then all of the outlets must be stopped.
Although the prior dual chamber blasting media machines are steps in the right direction the need for additional improvements still remains. The present invention satisfies this need in a novel and unobvious way.